Semiconductor chip fabrication processes generally include a micropattern-forming process on a wafer and a packaging process wherein a wafer is ground to the size of a final device.
The packaging process includes: a wafer testing process during which defective semiconductor chips are inspected; a dicing process in which a wafer is cut into individual chips; a die bonding process wherein the separate chips are attached to a mounting board of a circuit film or lead frame; a wire bonding process wherein a chip pad provided on a semiconductor chip is connected with a circuit pattern of the circuit film or lead frame via electrical connecting means such as wire; a molding process wherein the exterior of the semiconductor is wrapped with an enveloping material in order to protect the internal circuit and other parts of the semiconductor chip; a trimming process wherein a dam bar connecting leads is broken; a forming process wherein the leads are bent to obtain a desired form; and a final product testing process to inspect defects in a packaged product.
In a dicing process, a wafer is cut to a certain thickness by means of a diamond wheel or the like. Before dicing, a dicing die bonding film is laminated, under suitable temperature conditions, on the backside of a wafer in which patterns are not formed, in order to fix the wafer.
A dicing die bonding film generally includes a dicing tape and a die bonding film layered on the dicing tape. To the backside of a wafer which has no patterns, a die bonding film is used. In a dicing process, the whole wafer, and a part of a die bonding film and a dicing tape are cut using a diamond wheel (blade).
In such a dicing process, excessive pressure or mechanical impact is likely to be applied to a wafer, damaging or chipping the wafer, so that burrs which may cause contamination in the patterns frequently occur. As the thickness of wafers is being less, and with the tendency of small size packaging and severe dicing conditions to improve the production efficiency, problems caused by burrs or the like have been occurring more frequently. Particularly, with the use of a thinner wafer, burrs protrude to a level which did not used to cause a problem in the past, but now often stand out from the die causing defective products.
A conventional technique for reducing such burrs is to adjust a dicing tape and a die bonding film, specifically, a method for increasing the elasticity of a die bonding film.
Korean laid-open patent application No. 1999-7508 discloses an epoxy composition comprised of resinous components including an epoxy resin, a hardening agent, a diluent, a hardening accelerating agent and a thixotropic agent and an inorganic filler. The invention describes that the composition exhibits suitable elasticity which does not cause defects in wire bonding and has satisfactory adhesion strength. Japanese laid-open patent application No. 1998-46114 discloses a film type adhesive containing an adhesive layer comprising an adhesive resin of which the glass transition temperature (Tg) is 50° C. to 250° C. and, based on the weight of the adhesive resin (100 parts by weight), 10-400 parts by weight of an elastic filler.
The above-mentioned techniques are methods for increasing the film elasticity by increasing: the glass transition temperature of a thermoplastic resin contained in a die bonding film; the filler content; or the softening temperature of an epoxy or hardening agent. According to the foregoing methods, it is possible to increase the film elasticity; however, it causes deterioration in adhesive properties. Therefore, a film will not be attached to the back of a wafer, or after adhesion, the tack properties thereof are significantly reduced during a wire bonding or molding process, lowering workability and reliability in semiconductor fabrication.